This is a trifle odd. I spotted it on a bus side today and then did a spot of searching on t'interweb and came across this whole odd collaboration ... So basically, it transpires that adidas (of three stripes, sport, Run DMC, the shell toe, rock n roll trainers, Gazelles, Stan Smith, you know?) ...

I suspect the majority of registrations might not use a traditional form. However I think communities will continue to default to the old system - not everyone is going to be on Facebook or Twitter.
NB - just read that OpenID has hit 1Billion accounts:
http://www.readwriteweb.com/archives/openid_ends_2009_with_1_billion_users.php
Charlie
www.FreshNetworks.com

By the end of 2010, the majority of new online communities wont have a registration page. At least not in the sense we use today. Instead we will use accounts created elsewhere. This is a very good thing.